The present embodiments relate to electronic devices and are more particularly directed to an electronic device with a satellite positioning system receiving function, where the device performs positioning determinations in response, in part, to broadcasted Doppler information.
Electronic devices are extremely prevalent and beneficial in today's society and are constantly being improved due to consumer and user demand. One technological example has been the mobile or cellular telephone, which has seen great advances in the last many years. These devices have evolved beyond provision of voice services alone and are now accommodating greater amounts of data and are providing various additional features, more advanced operating systems, and additional programming. For example, so-called “smart phones” are envisioned as having a large impact on upcoming generations of cellular phones. As another example, various personal digital assistants (“PDAs”) are still succeeding in the marketplace and may do so for the foreseeable future. Further, the functionality of cellular phones and PDAs are now beginning to overlap with the possibility of a greater combination of the functionality of these devices into a single unit in the future.
With the advancement of the devices introduced above, various newer features are now being developed and implemented. One feature that is found in some past cellular phones and which is soon or already to be mandated in contemporary phones is the ability of the phone to report its geographical position of latitude, longitude, and altitude, as was recently driven by the E911 initiative. Per this initiative, such a feature may well serve beneficial when the phone's user places an emergency 911 call, whereby in response the phone then reports its geographic location so as to permit a better response to the call and the potential emergency that accompanies the call.
The ability of present cellular phones to report a geographic location of the phone has been provided by the phone using information from a satellite positioning system (“SPS”). Prior to its use in cellular phones, SPS has existed for decades and has been used in military and civil applications. The current SPS system includes the well-known US-owned global positioning satellite (“GPS”) system or NAVSTAR and the Russia-owned Global Navigation Satellite System (“GLONASS”). Additionally, the European Union has started its effort to support SPS with an initiative to position a constellation of satellites, called the Galileo system, for completion in the future. In any event, many cellular phones are now including an SPS functionality, whereby in general that functionality receives certain SPS information from satellites in order to determine a geographic location, which is sometimes referred to as either a location fix or a position fix.
In addition to receiving information from satellites, certain SPS receivers now receive additional SPS information, for use in detecting a location fix, from other sources. As one example, so-called assisted GPS (“AGPS”) has more recently been developed in an effort to expedite the ability of a GPS receiver to make its first fix determination, that is, to acquire sufficient information so as to provide a location fix (a process often called “acquisition”), after which subsequent location fixes may be ascertained relative to that first location fix. The time to make this first determination is sometimes referred to as TTFF, for “time to first fix.” In traditional GPS, TTFF may be on the order of minutes, which is workable in some instances but not superior in others. However, with AGPS, the TTFF has been reduced. In AGPS, high-performance reference receivers are added to a backbone network that is part of a cellular phone network, such as in the so-called mobile switching center of the network (which is also called by other names, depending on the cellular standard at issue). These reference receivers may operate full-time and are not constrained by the requirements that are often imposed on cell phone handsets, such as low power use and constrained device size and cost. Thus, the reference receivers may constantly receive information from the SPS, such as pseudo-random codes, ephemeris data, almanac data, and timing information. This information is then collected in a system coordinator device. Accordingly, when a cellular phone places a 911 call to the cellular backbone, and with the requirement that the phone at that time needs to determine its location fix, rather than requiring the TTFF of the phone to be constrained by awaiting information from satellites, more recently there has been proposed that the cellular system provides information from the coordinator device to the particular 911-calling cellular phone. Thus, such information is received by the phone in a requested and bi-directional sense, by it calling the cellular backbone system and in response receiving the GPS information from that system; consequently, the information is received more quickly than such information may be obtained by the phone from one or more satellites. As a result, the phone is able to reduce its TTFF and report its location fix more quickly as compared to using conventional GPS.
Various approaches of AGPS or otherwise providing SPS information to a remote device from a source other than the SPS system have been proposed. As an example, in U.S. Pat. No. 6,208,290, to Krasner, and entitled “GPS receiver utilizing a communication link,” there is proposed determining the approximate position of a cellular mobile unit at the cellular base station using time of arrival and determining and sending Doppler information to the mobile (or remote) unit based on that determination. As another example, in U.S. Pat. No. 6,064,336, to Krasner, and also entitled “GPS receiver utilizing a communication link,” there is proposed that the satellite almanac side information is sent from the cellular base station to the mobile unit and Doppler information is then derived by the mobile from the almanac information. As still another example, in U.S. Pat. No. 5,841,396, to Krasner, and also entitled “GPS receiver utilizing a communication link,” there is proposed the transmission of almanac data to a remote receiver that then determines Doppler data for certain GPS satellites. All of these approaches, therefore, require the mobile to have sufficient complexity and power so as to determine the Doppler information.
While the preceding approaches to providing SPS information to SPS-enabled devices have proven workable in certain implementations, the present inventors have observed that the preceding approaches also may provide certain drawbacks. For example, reliance on a singular source of SPS information (e.g., the cellular system) to facilitate expedited location fix determinations lacks redundancy, should the information-providing system fail or delay. As another example, AGPS may be undesirable where it is provided in a bi-directional sense and provides its information to the user device only in response to a request from the user device. As still another example, additional device complexity may be required when the mobile is expected to determine Doppler information. Finally, various of the above-described approaches are not necessarily readily advantageous when coupled into a mobile phone device. Still other examples will be ascertainable by one skilled in the art.
As a result of the preceding, there arises a need to address the drawbacks of the prior art as is achieved by the preferred embodiments described below.